Slide 1

ALDEHYDES AND KETONESSUBMITTED TO:MRS. SANGITA NORIASUBMITTED BY:8769,8773,8774,8775,8776,8777,8780,THE CARBONYL GROUP The carbonyl group (C=O) is found in aldehydes,ketones, and many other organic functional groups. The carbon and oxygen in the carbonyl group aresp2-hybridized, with bond angles of 120.

In ketones, two carbon groups are attached to thecarbonyl carbon, while in aldehydes at least onehydrogen is attached to the carbon

NOMENCLATUREALDEHYDESAldehydes are named by replacing the terminal -e of the corresponding alkane name with alThe parent chain must contain the CHO groupThe CHO carbon is numbered possible minimum number.

IUPACLONGEST CHAIN WITH ALDEHYDEDROP e AND ADD -alALDEYHYDE TAKES PRECEDENCE OVER ALL OTHER GROUPS SO FAR.EXAMPLES

ALDEHYDESNaming KetonesReplace the terminal -e of the alkane name with oneParent chain is the longest one that contains the ketone groupNumbering begins at the end nearer the carbonyl carbon

Ketones with Common NamesIUPAC retains well-used but unsystematic names for a few ketones

FORMATION OF ALDEHYDESOxidation of Primary Alcohols

The aldehyde can be oxidized in a second step[O] represent an oxidationOXIDATION OF SECONDARY ALCOHOLS

OXIDATION OF TERTIARY ALCOHOLS

OXIDATION OF PRIMARY ALCOHOLS TO ALDEHYDESRequires less vigorous oxidation conditions.

We can try to remove the aldehyde from the reaction medium as quickly as it is formed

Generally, the aldehyde has a lower boiling point than either the corresponding alcohol or carboxylic acid

We can also try to find a milder oxidizing agent.DEHYDROGENATION OVER COPPER

This reaction is generally done by passing the vapors of the alcohol through a tube furnace in a stream of inert carrier gas.This is not a practical laboratory method -- it is better suited to industrial processes.The reaction stops at the aldehyde stage -- no more removal of hydrogen can take place.Oxidation of Primary Alcohols with K2Cr2O7

This reaction can also be done using CrO3 (chromic oxide) in sulfuric acid.The aldehyde is distilled away from the reaction vessel as quickly as it is formed. If the aldehyde is not removed, it will suffer a second oxidation, and the product will be the carboxylic acid.The acidic conditions keep the chromium in the Cr2O72- state.Potassium dichromate is not as powerful an oxidizing agent as is potassium permanganateSodium dichromate can be substituted for potassium dichromate -- it makes no difference.There is a color change during the reaction. The orange color of the dichromate changes to the green of Cr3+ ion.This is not the worlds greatest way to prepare an aldehyde!OXIDATION WITH CHROMIC OXIDE AND PYRIDINE

Sarett OxidationOXIDATION WITH PYRIDINE CHLOROCHROMATE

PCC OxidationCHANGE OF GEARS:

Aldehydes can be oxidized to carboxylic acids.This oxidation can take place under very mild oxidizing conditions.Aldehydes can be oxidized with such weak oxidizing agents as metal cations, especially:Ag+ Cu2+